Researchers from the CSIRO-QUT Synthetic Biology Alliance have proven their modular approach to constructing small molecule biosensors — artificial proteins designed to capture biomarkers of choice and produce measurable responses — in collaboration with Clarkson University in the United States and Pathology Queensland.
In two separate studies, biosensors were adapted to accurately measure immunosuppressant drugs cyclosporine A, tacrolimus and rapamycin, and anticancer drug methotrexate, which requires close monitoring to reduce toxicity and organ damage.
Lead researcher Prof. Kirill Alexandrov says the protein biosensors had potential to expand patient care by enabling sophisticated tests on cheaper lab equipment and new point-of-care devices.
“Proteins are at the core of a $70 billion global diagnostic market that relies heavily on central lab processing,” Alexandrov says.
“Our biosensor technology will enable tests like therapeutic drug monitoring on less sophisticated equipment that you are more likely to find in small, regional, or remote labs and hospitals.”
Future tests may also require smaller biological samples with researchers proving a biosensor could accurately measure cyclosporine A levels in 1 μL blood samples.
“With further development, the biosensor technology could lead to a fingerstick test that potentially provides doctors with patient results in 3–5 minutes during a standard consultation,” Alexandrov says.
Alexandrov says protein complexity and fragility made construction and use of protein biosensors difficult, but the modular design helped alleviate the problem and could be adapted to potentially target any small molecule — not just therapeutic drugs.
He says the new proteins were produced by engineered bacteria, altered using recombinant DNA technology to produce artificial switch molecules that were tailored to recognize a particular drug.
“The protein biosensors are ‘switched off’ — like an electrical circuit with a missing piece. Only the targeted biochemical in human fluids like blood or saliva can complete the circuit and ’switch on’ a signal proportional to the amount of biomarker detected,” he says.
When activated, the different protein biosensors produce either a change of color for hue-based readings, or electrochemical current.
Alexandrov says the team experimented with applications using common glucometer technology to develop a cheap, portable, and accurate device.
“Activated electrochemical biosensors broke down glucose and generated electrons as by-products to produce electrical current proportional to the amount of captured target molecule,” he says.
“The Clarkson team also demonstrated the feasibility of multiplexing this technology to detect two different biomarkers at the same time.”
Despite experiment success, Alexandrov says glucometer technology was use-specific, and researchers would need to re-engineer devices and manufacturing processes for new clinical uses.
“There are a huge number of parameters to reconcile when building a medical device. It’s incredibly hard and that’s why new diagnostic technologies come to the market very slowly,” Alexandrov says.
Alexandrov is from the QUT Centre for Genomics and Personalized Health, the QUT Centre for Agriculture and the Bioeconomy, and the QUT Faculty of Science. He says future research would focus on protein biosensor stability, sensitivity, and manufacturability.
Studies validating different biosensor designs have been published by Angewandte Chemie and Nature Communications. The projects were supported with funding from QUT; Australian Research Council (ARC) Discovery Program; ARC Centre of Excellence in Synthetic Biology; Australian Government National Health and Medical Research Council (NHMRC); Human Frontiers Science Foundation (HFSF); and the U.S. Department of Defense.
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